Process of fabricating a whip antenna



May 24, 1960 E. F. HARRIS 2,933,210

PROCESS OF FABRICATING A WHIP ANTENNA Filed Sept. 30, 1957 [Pf/5 10c J9 J2 10 v .16

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BY Mf m aitomegs United States Edward F. Harris, 6412 W. Lincoln Ave., Morton Grove, Ill.

Filed Sept. 30, 1957, Ser. No. 687,286

3 Claims. (Cl. 343-895) My invention relates to a whip antenna and the process for fabricating same, the whip antenna having a tough protective integral covering, which does not impair its flexibility.

In certain types of whip antennas the conducting antenna wire is carried on a resilient core, usually in spiral conformations. It is desirable that the core and wire be covered to protect the assembly from the effects of weather, abrasion, and blows to which a whip antenna is subjected during normal use. In addition, it is desirable that the covering be an integral part of the antenna and firmly anchor the antenna wire in its position on the core, not only to prevent rubbing between the wire and the core, but to prevent any alteration in the electrical characteristics of the antenna which might result from any substantial change in the position, or conformation, of the wire on the core. It is, of course, necessary that the covering provided be flexible so as not to impair the flexibility of the antenna.

By the process set forth herein a whip antenna may be constructed with a tough protective covering forming an integral part of the antenna which will seal the antenna from the effects of weather, prevent wear, firmly hold the antenna wire in position, and make the antenna suitable for the most rugged operating conditions. In brief, the antenna wire is positioned on the resilient core. A flexible, expandable sleeve, having an inner diameter less than the diameter of the core, is soaked in a dilater solution until its diameter is large enough to receive the core and the antenna wire carried thereon. Thereupon the sleeve is removed from the dilater and the core and wire are inserted therein. The sleeve is allowed to dry on the core and shrink to form an integral, tough protective covering which embraces the core in gripping relationship. This protective covering seals and protects the antenna and yet will flex so that the flexibility or resiliency of the antenna is not substantially impaired.

It is therefore a general object of the present invention to provide a whip antenna suitable for rugged operating conditions and relatively unaffected by weather and a process for fabricating the same.

It is another object of the present invention to provide a whip antenna with an integral, tough protective covering that minimizes abrasion, corrosion, and damage from blows, and a process for fabricating the same.

It is a further object of the present invention to provide a whip antenna in which the protective covering of the antenna grips the antenna and anchors the antenna wire in position and a process for fabricatingthe same.

It is still another object of the present invention to provide a whip antenna in which the protective covering grips and seals the antenna without impairing its flexibility, or resiliency, and a process for fabricating the same.

It is yet another object of the present invention to provide a simple, inexpensive, process of manufacturing a whip antenna which requires a minimum of equipment atent hce and by which a rugged, effective antenna can be fabricated in a minimum of time.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention, together with further objects and advantages thereof, will best be understood by reference to the following description taken in conjunction with the accompanying drawings in which:

Figure 1 is an elevational view of a whip antenna constructed in accordance with the present invention, with a portion of the protective covering broken away for clarity;

Figure 2 is an enlarged fragmentary elevational view, partly in cross-section, of the antenna prior to installation of the protective covering;

Figure 3 is a view similar to Figure 2 showing the insertion of the flexible core and wire into the expanded sleeve, which is shown in cross-section; and

Figure 4 is a view similar to Figure 3 after the sleeve has shrunk to form a protective covering for the antenna, with a portion of the protective covering shown in crosssection.

Figure 1 shows a completed antenna constructed in accordance with the present invention. The antenna consists of a flexible core 10, a conducting wire 12 carried on the core, a ferrule 14 connected to one end of the core, a protective covering, or sleeve, 16, and a cap 18 placed over the other end of the core.

The initial steps of the process described herein are best understood by reference to Figure 2. The conducting wire 12 is positioned upon the core 10 in a manner to give the antenna the desired electrical characteristics. The wire may, for example, be wound in spiral conformations about the core as shown in Figure 2. The core 10, which may be tapered slightly, is made of a resilient material capable of holding an erect shape when supported at one end and which preferably is light weight and dielectric. Any resilient core with these characteristics may be used, but preferably the core is of glass composition, such as is commonly used in fishing rods, and may, for example, be made of molded glass fibers mechanically bound with a polyester resin.

The ferrule 14 is connected to one end of the core 10. The ferrule, which has a hexagonal conformation, has a cylindrical bore 14a in one end in which the core 10 is cemented. The ferrule has an extending threaded stub 14b at its opposite end which may be connected to any suitable mount. The ferrule has a passage 14c extending through the stud 14b and connecting to a hollowed center portion 14d of the ferrule. The conducting wire 12 passes through the end of the core 10 and is received in the ferrule to extend into the passage where it is soldered. The opposite end of the wire 12 is received in a slot 10a in the opposite end of the core 10 and is cemented therein.

The sleeve 16 which, after installation on the core an wire, constitutes a protective coating therefor, is soaked, prior to installation, in a dilater solution. The sleeve 16, prior to soaking, should have an inner diameter less than the smallest outer diameter of the core 10. The wall thickness of the sleeve should be sufficient to provide a tough protective coating for the antenna, but should not be so thick that the protective coating will substantially reduce the flexibility of the antenna. In an antenna constructed in accordance with the present invention, where the diameter of the resilient core 10 was tapered from 0.275 inch to 0.380 inch, a sleeve with an inner diameter, prior to treatment, of 0.250 inch and inch wall thickness was used. The wire conductor 12 was 22 gage, or 0.025 inch in diameter.

The sleeve, which must be flexible and must be expa'ndable when soaked in a dilater 'solution, may be made, for example, of any synthetic plastic, such as vinyl or polyethylene, which is flexible at normal temperature and capable of expanding in a dilater solution. Preferably extruded tubing is used as it provides a'tough, flexible covering.

The sleeve 16 is soaked ina dilater solution until it softens and expands. The dilater may be any solution which will have this effect on the material used for the sleeve, such as any lacquer thinner, alcohol, a solution with a naphtha base, or any volatile solvent. Indeed, even boiling water can be used to soften and expand the sleeve. In the fabrication of an antenna in accordance with the present invention, a large expansion of an extruded vinyl sleeve was achieved by immersion in General Electric solution 12501 for a period of approximately twenty four hours. t

After the expansion of the sleeve 16, the core carrying the conducting wire 12 is inserted therein, as shown in Figure 3. If necessary, the core and wire may be lubricated with a lubricant such as Vaseline or the Dow Chemical Company lubricant DC-4. This latter lubricant has the added advantage of tending to expel any moisture which may be present. Preferably, the sleeve is installed to extend from the top of the core 10 down over at least a portion of the ferrule 14 as shown in Figure 3.

Thereafter the sleeve 16 is allowed to dry on the core. The sleeve tends to shrink back to its original size and thereby grips the core 10, wire 12, and ferrule 14 to provide a protective covering as shown in Figure 4. This covering, while not substantially impairing the flexibility of the core, seals the core and conducting wire against corrosion, abrasion, and dirt. At the same time the covering securely holds the conducting wire on the core in its proper position. The covering provided by the process described herein is tough and is capable of withstanding blows to which it may be subjected in even the most rugged service.

The physical properties of the sleeve 16 are responsible for its suitability for the present antenna. The sleeve is made by an extrusion process, which forms a tough, unitary structure with extrusion markings extending along its length. Despite the large degree of tension on the sleeve (when the treating liquid evaporates), the sleeve, nevertheless, retains its unitary structure andwhen cut or otherwise injured--it does not propagate breaks or peel. Moreover, the sleeve deforms permanently on its inside surface where it seats over the wire 12, so that it embraces this wire more closely than otherwise would take place. Finally, the sleeve is of low weight, readily partakes of flexure of the antenna without adding substantial resistance thereto, and does not otherwise interfere with the attainment of highly effective whip antenna structure.

In order to completely seal the antenna a cap 18 may be installed over the end of the core 10 opposite the ferrule as shown in Figures 1 and 4. 7

While I have shown and described a specific embodiment of the present invention, it will, of course, be understood that other modifications and alternative construction may be used without departing from the true spirit and scope of this invention. I therefore intend by the appended claims to cover all such modifications and alternative construction as fall within their true scope.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. The process of fabricating a whip antenna of the type comprising a flexible core with a conducting wire thereabout and a covering about said core and wire, said process comprising the steps of: placing the conducting wire along the core; soaking a sleeve made of flexible expandable material of an inner diameter less than the diameter of the core in a dilater solution to expand the sleeve; thereafter inserting the core with the wire thereon within the dilated sleeve; evaporating the dilater from the sleeve to shrink the sleeve to embrace the core in gripping relationship and form a protective covering which will hold the conducting wire firmly in place and permit maximum flexure of the flexible core without fracture of the covering or displacement of the wire on the core.

2. The process of fabricating a whip antenna of the type comprising a flexible core with a conducting wire thereabout and a covering about said core and wire, said process comprising the steps of: winding the conducting wire in spiral conformations along the core; soaking a sleeve made of flexible expandable material of an inner diameter less than the diameter of the core in a dilater solution to expand the sleeve; applying a lubricant to the core and conducting wire; thereafter inserting the core with the wire thereon within the dilated sleeve; evaporating the dilater from the sleeve to shrink the sleeve to embrace the core in gripping relationship and form a protective covering which will hold the conducting wire firmly in place and permit maximum flexure of the flexible core without fracture of the covering or displacement of the wire on the core.

3. The process of fabricating a whip antenna of the type comprising a flexible tapered core with a conducting wire thereabout mounted in a ferrule and a covering about said core and wire, said process comprising the steps of: winding the conducting wire in spiral conformations along the core; cementing the ferrule at the end of the core of greatest diameter; soaking a sleeve made of flexible expandable material of an inner diameter less than the smallest diameter of the core in a dilater solution to expand the sleeve; applying a non-conducting lubricant to the core and conducting wire; thereafter inserting the narrow end of the core with the wire thereon in the dilated sleeve until the sleeve covers the entire span of the core extending from the ferrule and a portion of the ferrule; evaporating the dilater from the sleeve to shrink the sleeve to embrace the core in hoop tension and form a protective covering which will hold the conducting wire firmly in place and permit maximum flexure of the flexible core without fracture of the covering or displacement of the wire on the core.

spirit and References Cited in the file of this patent UNITED STATES PATENTS 2,681,412 Webster June 15, 1954 2,751,629 Dick June 26, 1956 2,763,003 Harris Sept. 11, 1956 

